Abstract: There is a need for people who handle hazardous materials to be able to effectively and efficiently block cesspits and/or pipes of various drainage systems in circumstances of for example, a chemical or liquid spill or a gas leak so as to prevent or limit flow of the same into for example, the water table. This problem is solved through the use of a man made fluid inlet or outlet passage, blocking assembly having an inflatable bladder operatively linked to a fluid communication element, one aspect of the element being adapted to receive a pressurised fluid supply wherein, when a pressurised fluid passes through the fluid communication element, the bladder is adapted to inflate to block the passage in a fluid type manner.